A high power Q-switched Ho YAG laser pumped by two Tm-fiber lasers

High efficient and high power 2μm room temperature Ho:YAG laser by two Tm-fiber lasers at 1.91μm was demonstrated. A maximum continuous wave output power of 55.6W was generated, corresponding to the slope efficiency of 61.3% with respect to the incident pump power. At 18kHz of the pulsed repetition frequency, we achieved a less than 31ns FWHM pulse, with the maximum output energy per pulse of 3.0mJ. A beam quality of M 2 <2.4 was achieved.